Fibers and Nonwoven Materials Prepared Therefrom

ABSTRACT

Described herein are fibers, nonwoven fabrics, and other nonwoven articles comprising a blend of at least one propylene-based elastomer and an impact copolymer. The impact copolymer is a reactor blend and comprises a propylene homopolymer component and a copolymer component, where the copolymer component comprises less than about 55 wt % ethylene-derived units, based on the weight of the copolymer component.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalApplication No. 61/836,513, filed Jun. 18, 2013, the disclosure of whichis fully incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to blends comprising propylene-based elastomersand fibers and nonwoven materials prepared therefrom.

BACKGROUND OF THE INVENTION

The use of various thermoplastic resins to make fibers and fabrics iswell known. In particular, propylene-based polymers and copolymers(sometimes referred to as propylene-based elastomers) are well known inthe art for their usefulness in a variety of applications, including themanufacture of nonwoven fabrics. Such fabrics have a wide variety ofuses, such as in medical and hygiene products, clothing, filter media,and sorbent products. Nonwoven fabrics are particularly useful inhygiene products, such as baby diapers, adult incontinence products, andfeminine hygiene products. An important aspect of these fabrics,particularly in hygiene applications, is the ability to produceaesthetically pleasing fabrics, i.e., fabrics that are soft to thetouch, and that have good leakage performance, i.e., fabrics that arestretchable and conform to the body of the wearer.

Propylene impact copolymers are commonly used in applications wherestrength and impact resistance is desired, such as in molded andextruded automobile parts, household appliances, luggage, and furniture.Though often used to make films, propylene impact copolymers are not ascommonly used to make fibers and fabrics because impact resistance isoften not a desired property for such applications. For fibers andfabrics, manufacturers focus on properties such as strength,processability, softness, and breathability. U.S. Pat. Nos. 6,248,833,6,440,882, and 7,319,122, U.S. Patent Application Nos. 2009/0311938,2009/0149605, and 2010/0124864, and PCT Application No.PCT/US2012/064592 describe fibers and fabrics prepared with impactcopolymers.

In many hygiene applications, multilayer nonwoven materials or laminatesare employed having at least one elastic core layer and at least oneextensible facing layer, where the elastic layer provides the desiredconformability and fit of the product (and therefore, good leakageperformance) while the extensible facing layer provides the desiredaesthetics. Propylene-based elastomers are often used to form theelastic layers, however, are often considered too rubbery in feel toprovide the desired aesthetics needed for the facing layer. Therefore,the facing layers are often composed of bicomponent polymer blends wherethe blend components are arranged in a core/sheath structure. Suchbicomponent blends may include homopolymers of propylene, homopolymersof ethylene, random propylene copolymers, and other propylene orethylene-based polymers, and blends thereof. The formation of suchbicomponent materials, however, adds complexity and expense to thenonwoven manufacturing processes. It would be desirable, then, toprovide monocomponent nonwoven fibers and fabrics having goodextensibility, spinability, and softness in spunmelt processes.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates the peak elongation of the fibers in Example 1.

FIG. 2 illustrates the peak elongation of the fibers in Example 2.

FIG. 3 illustrates the peak elongation of the fibers in Example 3.

SUMMARY OF THE INVENTION

Provided herein are fibers, nonwoven fabrics, and other nonwovenarticles comprising a blend of at least one propylene-based elastomerand an impact copolymer.

In some embodiments, the fiber may comprise a blend of from about 30 toabout 85 wt % of an impact copolymer and from about 15 to about 70 wt %of a propylene-based elastomer. The impact copolymer is a reactor blendand comprises a propylene homopolymer component and a copolymercomponent, where the copolymer component comprises less than 55 wt %ethylene-derived units, based on the weight of the copolymer component.The propylene-based elastomer comprises propylene and from about 5 wt %to about 25 wt % units derived from one or more C₂ or C₄-C₁₂alpha-olefins and has a MFR of greater than 20 g/10 min and a heat offusion less than about 75 J/g.

DETAILED DESCRIPTION OF THE INVENTION

Fibers, nonwoven fabrics, and other nonwoven articles comprising a blendof at least one propylene-based elastomer and an impact copolymer areprovided herein, as well as methods for forming the same.

As used herein, the term “copolymer” is meant to include polymers havingtwo or more monomers, optionally, with other monomers, and may refer tointerpolymers, terpolymers, etc. The term “polymer” as used hereinincludes, but is not limited to, homopolymers, copolymers, terpolymers,etc., and alloys and blends thereof. The term “polymer” as used hereinalso includes impact, block, graft, random, and alternating copolymers.The term “polymer” shall further include all possible geometricalconfigurations unless otherwise specifically stated. Such configurationsmay include isotactic, syndiotactic and random symmetries. The term“blend” as used herein refers to a mixture of two or more polymers. Theterm “elastomer” shall mean any polymer exhibiting some degree ofelasticity, where elasticity is the ability of a material that has beendeformed by a force (such as by stretching) to return at least partiallyto its original dimensions once the force has been removed.

The term “monomer” or “comonomer,” as used herein, can refer to themonomer used to form the polymer, i.e., the unreacted chemical compoundin the form prior to polymerization, and can also refer to the monomerafter it has been incorporated into the polymer, also referred to hereinas a “[monomer]-derived unit”. Different monomers are discussed herein,including propylene monomers, ethylene monomers, and diene monomers.

“Polypropylene,” as used herein, includes homopolymers and copolymers ofpropylene or mixtures thereof. Products that include one or morepropylene monomers polymerized with one or more additional monomers maybe more commonly known as random copolymers (RCP) or impact copolymers(ICP). Impact copolymers may also be known in the art as heterophasiccopolymers. “Propylene-based,” as used herein, is meant to include anypolymer comprising propylene, either alone or in combination with one ormore comonomers, in which propylene is the major component (i.e.,greater than 50 wt % propylene).

“Reactor grade,” as used herein, means a polymer that has not beenchemically or mechanically treated or blended after polymerization in aneffort to alter the polymer's average molecular weight, molecular weightdistribution, or viscosity. Particularly excluded from those polymersdescribed as reactor grade are those that have been visbroken orotherwise treated or coated with peroxide or other prodegradants. Forthe purposes of this disclosure, however, reactor grade polymers includethose polymers that are reactor blends.

“Reactor blend,” as used herein, means a highly dispersed andmechanically inseparable blend of two or more polymers produced in situ.For example, a reactor blend polymer may be the result of a sequential(or series) polymerization process where a first polymer component isproduced in a first reactor and a second polymer component is producedin a second reactor in the presence of the first polymer component.Alternatively, a reactor blend polymer may be the result of a parallelpolymerization process where the polymerization effluent containing thepolymer components made in separate parallel reactors are solutionblended to form the final polymer product. Reactor blends may beproduced in a single reactor, a series of reactors, or parallel reactorsand are reactor grade blends. Reactor blends may be produced by anypolymerization method, including batch, semi-continuous, or continuoussystems. Particularly excluded from “reactor blend” polymers are blendsof two or more polymers in which the polymers are blended ex situ, suchas by physically or mechanically blending in a mixer, extruder, or othersimilar device.

“Visbreaking,” as used herein, is a process for reducing the molecularweight of a polymer by subjecting the polymer to chain scission. Thevisbreaking process also increases the MFR of a polymer and may narrowits molecular weight distribution. Several different types of chemicalreactions can be employed for visbreaking propylene-based polymers. Anexample is thermal pyrolysis, which is accomplished by exposing apolymer to high temperatures, e.g., in an extruder at 270° C. or higher.Other approaches are exposure to powerful oxidizing agents and exposureto ionizing radiation. A commonly used method of visbreaking is theaddition of a prodegradant to the polymer. A prodegradant is a substancethat promotes chain scission when mixed with a polymer, which is thenheated under extrusion conditions. Examples of prodegradants used incommercial practice are alkyl hydroperoxides and dialkyl peroxides.These materials, at elevated temperatures, initiate a free radical chainreaction resulting in scission of polypropylene molecules. The terms“prodegradant” and “visbreaking agent” are used interchangeably herein.Polymers that have undergone chain scission via a visbreaking processare said herein to be “visbroken.” Such visbroken polymer grades,particularly polypropylene grades, are often referred to in the industryas “controlled rheology” or “CR” grades.

“Catalyst system,” as used herein, means the combination of one or morecatalysts with one or more activators and, optionally, one or moresupport compositions. An “activator” is any compound or component, orcombination of compounds or components, capable of enhancing the abilityof one or more catalysts to polymerize monomers to polymers.

As used herein, “nonwoven fabric” means a web structure of individualfibers or filaments that are interlaid, but not in an identifiablemanner as in a knitted fabric.

Impact Copolymers

The impact copolymers (“ICPs”) useful for making the fibers and fabricsof the invention comprise at least two components, Component A andComponent B. Component A is preferably a propylene homopolymer andComponent B is preferably a copolymer comprising propylene andcomonomer.

In preferred embodiments, Component A is a propylene homopolymer, andpreferably an isotactic propylene homopolymer, although small amounts ofa comonomer may be used to obtain particular properties. Typically, suchcopolymers contain less than 10 wt %, or less than 6 wt %, or less than4 wt %, or less than 2 wt %, or less than 1 wt % of comonomer such asethylene, butene, hexene or octene. Preferably, the polymer component ofComponent A consists essentially of propylene-derived units and does notcontain any comonomer except that which may be present due to impuritiesin the propylene feed stream.

In some embodiments, Component A consists only of propylene-derivedunits.

Component A may have molecular weight distribution, Mw/Mn (“MWD”), i.e.,greater than 1.0, or greater than 2.0, or greater than 2.5, or greaterthan 3.0, or greater than 3.5. Preferably, Component A has a MWD of lessthan 7.0, or less than 6.0, or less than 5.5, or less than 5.0, or lessthan 4.5. In some embodiments, Component A has a MWD in the range offrom 1.0 to 7.0, or in the range of from 2.0 to 6.0, or in the range offrom 3.0 to 5.0, or in the range of from 3.5 to 4.5. In certainembodiments, these molecular weight distributions are obtained in theabsence of visbreaking using peroxide or other post reactor treatmentdesigned to reduce molecular weight.

As used herein, MWD is determined according to methods well known in theart, for example by GPC (Gel Permeation Chromatography) on a Waters 150gel permeation chromatograph equipped with a differential refractiveindex (DRI) detector and a Chromatix KMX-6 on line light scatteringphotometer. The system is used at 135° C. with 1,2,4-trichlorobenzene asthe mobile phase using Shodex (Showa Denko America, Inc.) polystyrenegel columns 802, 803, 804, and 805. This technique is discussed in“Liquid Chromatography of Polymers and Related Materials III,” J. Cazeseditor, Marcel Dekker, 1981, p. 207, which is incorporated herein byreference. No corrections for column spreading are employed; however,data on generally accepted standards, e.g., National Bureau of StandardsPolyethylene 1484 and anionically produced hydrogenated polyisoprenes(alternating ethylene-propylene copolymers) demonstrate that suchcorrections on MWD are less than 0.05 units. M_(w), M_(n), and M_(z) arecalculated from elution times. The numerical analyses are performedusing the commercially available Beckman/CIS customized low-anglelaser-light scattering (“LALLS”) software in conjunction with thestandard Gel Permeation package. Reference to M_(w)/M_(n) implies thatthe M_(w) is the value reported using the LALLS detector and M_(n) isthe value reported using the DRI detector described above.

Component A may have a weight average molecular weight (Mw, asdetermined by GPC) of less than 400,000, or less than 350,000, or lessthan 300,000, or less than 275,000, or less than 250,000.

Component A may have a melting point (Tm) of at least 150° C.,preferably at least 155° C., most preferably at least 160° C. Themelting point may be determined by differential scanning calorimetry(DSC), by taking a sample weight of 5-7 mg and melting completely thepolymer at 200° C. for a minute and then cooling at 10° C./min andrecording the crystallization temperature, followed by melting endothermunder second heating cycle.

In some embodiments, the melt flow rate (“MFR”) of Component A may begreater than 50 g/10 min, or greater than 55 g/10 m, or greater than 60g/10 m, or greater than 65 g/10 m, or greater than 70 g/10 m, or greaterthan 75 g/10 m, or greater than 80 g/10 min, or greater than 85 g/10 m,or greater than 90 g/10 m, or greater than 95 g/10 min, or greater than100 g/10 m, or greater than 110 g/10 min, or greater than 120 g/10 m, orgreater than 130 g/10 m, or greater than 140 g/10 m, or greater than 150g/10 min. The MFR of Component A may be less than 500 g/10 m, or lessthan 450 g/10 m, or less than 400 g/10 min, or less than 350 g/10 m, orless than 300 g/10 min, or less than 250 g/10 min, or less than 200 g/10min, or less than 175 g/10 min. In some embodiments, the MFR ofComponent A may range from about 50 to about 500 g/10 min, or from about60 to about 475 g/10 min, or from about 65 to about 450 g/10 min, orfrom about 100 to about 500 g/10 min, or from about 110 to about 400g/10 min, or from about 120 to about 300 g/10 min, or from about 130 toabout 200 g/10 min, or from about 140 to about 200 g/10 min. The MFR maybe determined by ASTM-1238 measured at load of 2.16 kg and 230° C.

In preferred embodiments, Component B is a copolymer comprisingpropylene and comonomer. The comonomer is preferably ethylene, althoughother propylene copolymers or terpolymers may be suitable depending onthe particular product properties desired. For example propylene/butene,hexene, or octene copolymers may be used.

Component B preferably comprises at least 40 wt % propylene, or at least45 wt % propylene, or at least 50 wt % propylene, or at least 51 wt %propylene, or at least 52 wt % propylene, or at least 53 wt % propylene,or at least 55 wt % propylene, or at least 57 wt % propylene, or atleast 60 wt % propylene, or at least 62 wt % propylene, or at least 65wt % propylene. Component B may comprise less than 95 wt % propylene, orless than 80 wt % propylene, or less than 75 wt % propylene, or lessthan 70 wt % propylene, or less than 65 wt % propylene, or less than 60wt % propylene, or less than 58 wt % propylene. In some embodiments,Component B comprises from about 40 wt % to about 95 wt % propylene, orfrom about 45 wt % to about 80 wt % propylene, or from about 50 wt % toabout 70 wt % propylene.

Component B preferably comprises at least 5 wt % comonomer, or at least10 wt % comonomer, or at least 15 wt % comonomer, or at least 25 wt %comonomer, or at least 30 wt % comonomer, or at least 35 wt % comonomer,or at least 40 wt % comonomer, or at least 42 wt % comonomer. ComponentB may comprise less than 60 wt % comonomer, or less than 58 wt %comonomer, or less than 55 wt % comonomer, or less than 53 wt %comonomer, or less than 52 wt % comonomer, or less than 50 wt %comonomer, or less than 49 wt % comonomer, or less than 48 wt %comonomer, or less than 47 wt % comonomer, or less than 46 wt %comonomer, or less than 45 wt % comonomer, or less than 40 wt %comonomer, or less than 35 wt % comonomer. In some embodiments,Component B comprises from about 5 to about 60 wt % comonomer, or fromabout 15 to about 55 wt % comonomer, or from about 20 to about 50 wt %comonomer, or from about 25 to about 47 wt % comonomer, or from about 30to about 47 wt % comonomer, or from about 30 to about 45 wt % comonomer.In some embodiments, Component B comprises from about 35 to about 55 wt% comonomer, or from about 40 to about 52 wt % comonomer, or from about43 to about 50 wt % comonomer, with the balance being propylene. Incertain embodiments, Component B may consist essentially of propyleneand ethylene in the above described amounts.

In one or more embodiments, Component B may have an intrinsic viscositygreater than 1.00 dl/g, or greater than 1.50 dl/g, or greater than 1.75dl/g. Component B may have an intrinsic viscosity of less than 5.00dl/g, or less than 4.00 dl/g, or less than 3.50 dl/g. The term“intrinsic viscosity” or “IV” is used herein to mean the viscosity of asolution of polymer such as Component B in a given solvent at a giventemperature, when the polymer composition is at infinite dilution.According to the ASTM D1601 standard, IV measurement utilizes a standardcapillary viscosity measuring device, in which the viscosity of a seriesof concentrations of the polymer in the solvent at a given temperatureare determined. For Component B, decalin is a suitable solvent and atypical temperature is 135° C. From the values of the viscosity ofsolutions of varying concentrations, the viscosity at infinite dilutioncan be determined by extrapolation.

The ICPs may comprise from about 40 to about 95 wt % Component A andfrom about 5 to about 60 wt % Component B, or from about 50 to about 90wt % Component A and from about 10 to about 50 wt % Component B, or fromabout 60 to about 90 wt % Component A and from about 10 to about 40 wt %Component B, or from about 70 to about 85 wt % Component A and fromabout 15 to about 30 wt % Component B, where desirable ranges mayinclude ranges from any lower limit to any upper limit. In someembodiments, the ICP may consist essentially of Components A and B.

The overall comonomer (e.g., ethylene) content of the ICP may be in therange of from about 3 wt % to about 40 wt %, or from about 5 wt % toabout 25 wt %, or from about 6 wt % to about 20 wt %, or from about 7 wt% to about 15 wt %, where desirable ranges may include ranges from anylower limit to any upper limit.

The melt flow rate (“MFR”) of the ICPs suitable for use herein may rangefrom about 5 to about 1000 g/10 min, or from about 10 to about 750 g/10min, or from about 15 to about 500 g/10 min, or from about 20 to about250 g/10 min, or from about 25 to about 100 g/10 min, or from about 30to 60 g/10 min. The MFR may be determined by ASTM-1238 measured at loadof 2.16 kg and 230° C., where desirable ranges may include ranges fromany lower limit to any upper limit.

The ICPs suitable for use in the polymer blends of the present inventionmay, in some embodiments, be reactor blends, meaning that Components Aand B are not physically or mechanically blended together afterpolymerization but are interpolymerized in at least one reactor, oftenin two or more reactors in series. The final ICP as obtained from thereactor or reactors, however, can be blended with various othercomponents including other polymers or additives. In other embodiments,however, the ICPs described herein may be formed by producing ComponentsA and B in separate reactors and physically blending the components oncethey have exited their respective reactors.

In one or more embodiments herein, the ICPs may be described as“heterophasic.” As used herein, heterophasic means that the polymershave two or more phases. Commonly, heterophasic ICPs comprise a matrixcomponent in one phase and a second rubber component phase dispersedwithin the matrix. In one or more embodiments herein, the ICPs comprisea matrix phase comprising a propylene homopolymer (Component A) and adispersed phase comprising a propylene-ethylene copolymer (Component B).The copolymer component (Component B) has rubbery characteristics andprovides impact resistance, while the matrix component (Component A)provides overall stiffness.

A variety of additives may be incorporated into the ICP for variouspurposes. For example, such additives include, but are not limited to,stabilizers, antioxidants, fillers, colorants, nucleating agents, andmold release agents. Primary and secondary antioxidants include, forexample, hindered phenols, hindered amines, and phosphates. Nucleatingagents include, for example, sodium benzoate, and talc. Dispersingagents such as Acrowax C can also be included. Slip agents include, forexample, oleamide, and erucamide. Catalyst deactivators are alsocommonly used, for example, calcium stearate, hydrotalcite, and calciumoxide.

The ICP compositions suitable for use in the present invention may beprepared by conventional polymerization techniques. For example, the ICPmay be produced using a two-step gas phase process using Ziegler-Nattacatalysis, an example of which is described in U.S. Pat. No. 4,379,759.The ICPs for use in the invention may also be produced in reactorsoperated in series. In such series operations, the first polymerization(polymerization of Component A) may be a liquid slurry or solutionpolymerization process, and the second polymerization (polymerization ofComponent B) may be carried out in the gas phase. In one or moreembodiments, hydrogen may be added to one or both reactors to controlmolecular weight, IV, and/or MFR. The use of hydrogen for such purposesis well known to those skilled in the art.

In some embodiments, the ICP is prepared using a Ziegler-Natta catalystsystem with a blend of electron donors as described in U.S. Pat. No.6,087,459 or U.S. Patent Application Publication No. 2010/0105848. Insome embodiments, the ICP may be prepared using a succinateZiegler-Natta type catalyst system.

Metallocene-based catalyst systems may also be used to produce the ICPcompositions described herein. Current particularly suitablemetallocenes are those in the generic class of bridged, substitutedbis(cyclopentadienyl) metallocenes, specifically bridged, substitutedbis(indenyl) metallocenes known to produce high molecular weight, highmelting, highly isotactic propylene polymers. Generally speaking, thoseof the generic class disclosed in U.S. Pat. No. 5,770,753 are suitable.

It has been found that the ICPs described above are particularly usefulfor producing fibers, nonwoven fabrics, and multilayer laminates whenblended with one or more propylene-based elastomers (PBEs) as describedbelow.

Propylene-Based Elastomers

The polymer blends used to form the fibers and fabrics described hereincomprise one or more propylene-based elastomers (“PBEs”). The PBEcomprises propylene and from about 5 to about 25 wt % of one or morecomonomers selected from ethylene and/or C₄-C₁₂ α-olefins. The α-olefincomonomer units may be derived from ethylene, butene, pentene, hexene,4-methyl-1-pentene, octene, or decene. In preferred embodiments theα-olefin is ethylene. In some embodiments, the propylene-based polymercomposition consists essentially of propylene and ethylene, or consistsonly of propylene and ethylene. The embodiments described below arediscussed with reference to ethylene as the α-olefin comonomer, but theembodiments are equally applicable to other copolymers with otherα-olefin comonomers. In this regard, the copolymers may simply bereferred to as propylene-based polymers with reference to ethylene asthe α-olefin.

The PBE may include at least about 5 wt %, at least about 6 wt %, atleast about 7 wt %, or at least about 8 wt %, or at least about 9 wt %,or at least about 10 wt %, or at least about 12 wt % ethylene-derivedunits, where the percentage by weight is based upon the total weight ofthe propylene-derived and ethylene-derived units. The PBE may include upto about 30 wt %, or up to about 25 wt %, or up to about 22 wt %, or upto about 20 wt %, or up to about 19 wt %, or up to about 18 wt %, or upto about 17 wt % ethylene-derived units, where the percentage by weightis based upon the total weight of the propylene-derived andethylene-derived units. In some embodiments, the PBE may comprise fromabout 5 wt % to about 25 wt % ethylene-derived units, or from about 7 wt% to about 20 wt % ethylene, or from about 9 wt % to about 18 wt %ethylene-derived units, where the percentage by weight is based upon thetotal weight of the propylene-derived and ethylene-derived units.

The PBE may include at least about 70 wt %, or at least about 75 wt %,or at least about 80 wt %, or at least about 81 wt % propylene-derivedunits, or at least about 82 wt %, or at least about 83 wt %propylene-derived units, where the percentage by weight is based uponthe total weight of the propylene-derived and α-olefin derived units.The PBE may include up to about 95 wt %, or up to about 94 wt %, or upto about 93 wt %, or up to about 92 wt %, or up to about 90 wt %, or upto about 88 wt % propylene-derived units, where the percentage by weightis based upon the total weight of the propylene-derived and α-olefinderived units.

The PBEs of one or more embodiments are characterized by a melting point(Tm), which can be determined by differential scanning calorimetry(DSC). For purposes herein, the maximum of the highest temperature peakis considered to be the melting point of the polymer. A “peak” in thiscontext is defined as a change in the general slope of the DSC curve(heat flow versus temperature) from positive to negative, forming amaximum without a shift in the baseline where the DSC curve is plottedso that an endothermic reaction would be shown with a positive peak. TheTm of the PBE (as determined by DSC) may be less than about 115° C., orless than about 110° C., or less than about 100° C., or less than about95° C., or less than about 90° C. In some embodiments, the PBE may havetwo melting peaks as determined by DSC. In other embodiments, the PBEmay have a single melting peak as determined by DSC.

The PBE may be characterized by its heat of fusion (Hf), as determinedby DSC. The PBE may have an Hf that is at least about 0.5 J/g, or atleast about 1.0 J/g, or at least about 1.5 J/g, or at least about 3.0J/g, or at least about 4.0 J/g, or at least about 5.0 J/g, or at leastabout 6.0 J/g, or at least about 7.0 J/g. The PBE may be characterizedby an Hf of less than about 75 J/g, or less than about 70 J/g, or lessthan about 60 J/g, or less than about 50 J/g, or less than about 45 J/g,or less than about 40 J/g, or less than about 35 J/g, or less than about30 J/g, or less than 25 J/g.

As used within this specification, DSC procedures for determining Tm andHf include the following. The polymer is pressed at a temperature offrom about 200° C. to about 230° C. in a heated press, and the resultingpolymer sheet is hung, under ambient conditions, in the air to cool.About 6 to 10 mg of the polymer sheet is removed with a punch die. This6 to 10 mg sample is annealed at room temperature for about 80 to 100hours. At the end of this period, the sample is placed in a DSC (PerkinElmer Pyris One Thermal Analysis System) and cooled to about −30° C. toabout −50° C. and held for 10 minutes at that temperature. The sample isheated at 10° C./min to attain a final temperature of about 200° C. Thesample is kept at 200° C. for 5 minutes. Then a second cool-heat cycleis performed. Events from both cycles are recorded. The thermal outputis recorded as the area under the melting peak of the sample, whichtypically occurs between about 0° C. and about 200° C. It is measured inJoules and is a measure of the Hf of the polymer.

The PBE can have a triad tacticity of three propylene units (mmmtacticity), as measured by 13C NMR, of 75% or greater, 80% or greater,85% or greater, 90% or greater, 92% or greater, 95% or greater, or 97%or greater. In one or more embodiments, the triad tacticity may rangefrom about 75 to about 99%, or from about 80 to about 99%, or from about85 to about 99%, or from about 90 to about 99%, or from about 90 toabout 97%, or from about 80 to about 97%. Triad tacticity is determinedby the methods described in U.S. Pat. No. 7,232,871.

The PBE may have a tacticity index m/r ranging from a lower limit of 4or 6 to an upper limit of 8 or 10 or 12. The tacticity index, expressedherein as “m/r”, is determined by ¹³C nuclear magnetic resonance(“NMR”). The tacticity index, m/r, is calculated as defined by H. N.Cheng in Vol. 17, MACROMOLECULES, pp. 1950-1955 (1984), incorporatedherein by reference. The designation “m” or “r” describes thestereochemistry of pairs of contiguous propylene groups, “m” referringto meso and “r” to racemic. An m/r ratio of 1.0 generally describes asyndiotactic polymer, and an m/r ratio of 2.0 describes an atacticmaterial. An isotactic material theoretically may have a ratioapproaching infinity, and many by-product atactic polymers havesufficient isotactic content to result in ratios of greater than 50.

The PBE may have a % crystallinity of from about 0.5% to about 40%, orfrom about 1% to about 30%, or from about 5% to about 25%, determinedaccording to DSC procedures, where desirable ranges may include rangesfrom any lower limit to any upper limit. Crystallinity may be determinedby dividing the Hf of a sample by the Hf of a 100% crystalline polymer,which is assumed to be 189 J/g for isotactic polypropylene or 350 J/gfor polyethylene.

The PBE may have a density of from about 0.85 g/cm³ to about 0.92 g/cm³,or from about 0.86 g/cm³ to about 0.90 g/cm³, or from about 0.86 g/cm³to about 0.89 g/cm³ at room temperature, as measured per the ASTM D-792test method, where desirable ranges may include ranges from any lowerlimit to any upper limit.

The PBE can have a melt index (MI) (ASTM D-1238, 2.16 kg @ 190° C.), ofless than or equal to about 100 g/10 min, or less than or equal to about50 g/10 min, or less than or equal to about 25 g/10 min, or less than orequal to about 10 g/10 min, or less than or equal to about 9.0 g/10 min,or less than or equal to about 8.0 g/10 min, or less than or equal toabout 7.0 g/10 min.

The PBE may have a melt flow rate (MFR), as measured according to ASTMD-1238 (2.16 kg weight @ 230° C.), greater than about 5 g/10 min, orgreater than about 8 g/10 min, or greater than about 10 g/10 min, orgreater than about 15 g/10 min, or greater than about 20 g/10 min, orgreater than about 25 g/10 min, or greater than about 30 g/10 min, orgreater than about 35 g/10 min, or greater than about 40 g/10 min, orgreater than about 43 g/10 min, or greater than about 45 g/10 min. ThePBE may have an MFR less than about 500 g/10 min, or less than about 400g/10 min, or less than about 300 g/10 min, or less than about 200 g/10min, or less than about 100 g/10 min, or less than about 75 g/10 min, orless than about 70 g/10 min, or less than about 60 g/10 min. In someembodiments, the PBE may have an MFR from about 20 to about 100 g/10min, or from about 30 to about 75 g/10 min, or from about 40 to about 60g/10 min.

In some embodiments, the PBE may be a reactor grade polymer, as definedabove. In other embodiments, the PBE may be a polymer that has beenvisbroken after exiting the reactor to increase the MFR. “Visbreaking”as used herein is a process for reducing the molecular weight of apolymer by subjecting the polymer to chain scission. The visbreakingprocess also increases the MFR of a polymer and may narrow its molecularweight distribution.

The PBE may have a g′ index value of 0.95 or greater, or at least 0.97,or at least 0.99, wherein g′ is measured at the Mw of the polymer usingthe intrinsic viscosity of isotactic polypropylene as the baseline. Foruse herein, the g′ index is defined as:

$g^{\prime} = \frac{\eta_{b}}{\eta_{l}}$

where ηb is the intrinsic viscosity of the polymer and ηl is theintrinsic viscosity of a linear polymer of the same viscosity-averagedmolecular weight (Mv) as the polymer. ηl=KMvα, K and α are measuredvalues for linear polymers and should be obtained on the same instrumentas the one used for the g′ index measurement.

The PBE may have a weight average molecular weight (Mw) of from about50,000 to about 5,000,000 g/mol, or from about 75,000 to about 1,000,000g/mol, or from about 100,000 to about 500,000 g/mol, or from about125,000 to about 300,000 g/mol, where desirable ranges may includeranges from any lower limit to any upper limit.

The PBE may have a number average molecular weight (Mn) of from about2,500 to about 2,500,000 g/mole, or from about 5,000 to about 500,000g/mole, or from about 10,000 to about 250,000 g/mole, or from about25,000 to about 200,000 g/mole, where desirable ranges may includeranges from any lower limit to any upper limit.

The PBE may have a Z-average molecular weight (Mz) of from about 10,000to about 7,000,000 g/mole, or from about 50,000 to about 1,000,000g/mole, or from about 80,000 to about 700,000 g/mole, or from about100,000 to about 500,000 g/mole, where desirable ranges may includeranges from any lower limit to any upper limit.

The molecular weight distribution (MWD, equal to Mw/Mn) of the PBE maybe from about 1 to about 40, or from about 1 to about 15, or from about1.8 to about 5, or from about 1.8 to about 3, where desirable ranges mayinclude ranges from any lower limit to any upper limit.

Optionally, the propylene-based polymer compositions may also includeone or more dienes. The term “diene” is defined as a hydrocarboncompound that has two unsaturation sites, i.e., a compound having twodouble bonds connecting carbon atoms. Depending on the context, the term“diene” as used herein refers broadly to either a diene monomer prior topolymerization, e.g., forming part of the polymerization medium, or adiene monomer after polymerization has begun (also referred to as adiene monomer unit or a diene-derived unit). Exemplary dienes include,but are not limited to, butadiene, pentadiene, hexadiene (e.g.,1,4-hexadiene), heptadiene (e.g., 1,6-heptadiene), octadiene (e.g.,1,6-octadiene, or 1,7-octadiene), nonadiene (e.g., 1,8-nonadiene),decadiene (e.g., 1,9-decadiene), undecadiene (e.g., 1,10-undecadiene),dodecadiene (e.g., 1,11-dodecadiene), tridecadiene (e.g.,1,12-tridecadiene), tetradecadiene (e.g., 1,13-tetradecadiene),pentadecadiene, hexadecadiene, heptadecadiene, octadecadiene,nonadecadiene, icosadiene, heneicosadiene, docosadiene, tricosadiene,tetracosadiene, pentacosadiene, hexacosadiene, heptacosadiene,octacosadiene, nonacosadiene, triacontadiene, and polybutadienes havinga molecular weight (Mw) of less than 1000 g/mol. Examples of branchedchain acyclic dienes include, but are not limited to5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, and3,7-dimethyl-1,7-octadiene. Examples of single ring alicyclic dienesinclude, but are not limited to 1,4-cyclohexadiene, 1,5-cyclooctadiene,and 1,7-cyclododecadiene. Examples of multi-ring alicyclic fused andbridged ring dienes include, but are not limited to tetrahydroindene;norbornadiene; methyltetrahydroindene; dicyclopentadiene;bicyclo(2.2.1)hepta-2,5-diene; and alkenyl-, alkylidene-, cycloalkenyl-,and cylcoalkylidene norbornenes [including, e.g.,5-methylene-2-norbornene, 5-ethylidene-2-norbornene,5-propenyl-2-norbornene, 5-isopropylidene-2-norbornene,5-(4-cyclopentenyl)-2-norbornene, 5-cyclohexylidene-2-norbornene, and5-vinyl-2-norbornene]. Examples of cycloalkenyl-substituted alkenesinclude, but are not limited to vinyl cyclohexene, allyl cyclohexene,vinylcyclooctene, 4-vinylcyclohexene, allyl cyclodecene,vinylcyclododecene, and tetracyclododecadiene. In some embodiments ofthe present invention, the diene is selected from5-ethylidene-2-norbornene (ENB); 1,4-hexadiene; 5-methylene-2-norbornene(MNB); 1,6-octadiene; 5-methyl-1,4-hexadiene;3,7-dimethyl-1,6-octadiene; 1,3-cyclopentadiene; 1,4-cyclohexadiene;vinyl norbornene (VNB); dicyclopentadiene (DCPD), and combinationsthereof. In embodiments where the propylene-based polymer compositionscomprises a diene, the diene may be present at from 0.05 wt % to about 6wt % diene-derived units, or from about 0.1 wt % to about 5.0 wt %diene-derived units, or from about 0.25 wt % to about 3.0 wt %diene-derived units, or from about 0.5 wt % to about 1.5 wt %diene-derived units, where the percentage by weight is based upon thetotal weight of the propylene-derived, alpha-olefin derived, anddiene-derived units.

In one or more embodiments, the PBE can optionally be grafted (i.e.,“functionalized”) using one or more grafting monomers. As used herein,the term “grafting” denotes covalent bonding of the grafting monomer toa polymer chain of the PBE. The grafting monomer can be or include atleast one ethylenically unsaturated carboxylic acid or acid derivative,such as an acid anhydride, ester, salt, amide, imide, acrylates, or thelike. Illustrative monomers include, but are not limited to acrylicacid, methacrylic acid, maleic acid, fumaric acid, itaconic acid,citraconic acid, mesaconic acid, maleic anhydride, 4-methylcyclohexene-1,2-dicarboxylic acid anhydride,bicyclo(2.2.2)octene-2,3-dicarboxylic acid anhydride,1,2,3,4,5,8,9,10-octahydronaphthalene-2,3-dicarboxylic acid anhydride,2-oxa-1,3-diketospiro(4.4)nonene, bicyclo(2.2.1)heptene-2,3-dicarboxylicacid anhydride, maleopimaric acid, tetrahydrophthalic anhydride,norbornene-2,3-dicarboxylic acid anhydride, nadic anhydride, methylnadic anhydride, himic anhydride, methyl himic anhydride, and5-methylbicyclo(2.2.1)heptene-2,3-dicarboxylic acid anhydride. Othersuitable grafting monomers include methyl acrylate and higher alkylacrylates, methyl methacrylate and higher alkyl methacrylates, acrylicacid, methacrylic acid, hydroxy-methyl methacrylate, hydroxyl-ethylmethacrylate and higher hydroxy-alkyl methacrylates and glycidylmethacrylate. Maleic anhydride is a preferred grafting monomer. In oneor more embodiments, the grafted PBE comprises from about 0.5 to about10 wt % ethylenically unsaturated carboxylic acid or acid derivative,more preferably from about 0.5 to about 6 wt %, more preferably fromabout 0.5 to about 3 wt %; in other embodiments from about 1 to about 6wt %, more preferably from about 1 to about 3 wt %. In a preferredembodiment wherein the graft monomer is maleic anhydride, the maleicanhydride concentration in the grafted polymer is preferably in therange of about 1 to about 6 wt %, preferably at least about 0.5 wt %,and highly preferably about 1.5 wt %.

In some embodiments, the PBE is a reactor blend of a first polymercomponent and a second polymer component. Thus, the comonomer content ofthe PBE can be adjusted by adjusting the comonomer content of the firstpolymer component, adjusting the comonomer content of second polymercomponent, and/or adjusting the ratio of the first polymer component tothe second polymer component present in the propylene-based polymercomposition. In such embodiments, the first polymer component maycomprise propylene and ethylene and have an ethylene content of greaterthan 10 wt % ethylene, or greater than 12 wt % ethylene, or greater than13 wt % ethylene, or greater than 14 wt % ethylene, or greater than 15wt % ethylene, and an ethylene content that is less than 20 wt %ethylene, or less than 19 wt % ethylene, or less than 18 wt % ethylene,or less than 17 wt % ethylene, or less than 16 wt % ethylene, where thepercentage by weight is based upon the total weight of thepropylene-derived and ethylene derived units of the first polymercomponent. In such embodiments, the second polymer component maycomprise propylene and ethylene and have an ethylene content of greaterthan 2 wt % ethylene, or greater than 3 wt % ethylene, or greater than 4wt % ethylene, or greater than 5 wt % ethylene, or greater than 6 wt %ethylene, and an ethylene content that is less than 10 wt % ethylene, orless than 9.0 wt % ethylene, or less than 8 wt % ethylene, or less than7 wt % ethylene, or less than 6 wt % ethylene, or less than 5 wt %ethylene, where the percentage by weight is based upon the total weightof the propylene-derived and ethylene derived units of the secondpolymer component. In such embodiments, the PBE may comprise from 3 to25 wt % of the second polymer component, or from 5 to 20 wt % of thesecond polymer component, or from 7 to 18 wt % of the second polymercomponent, or from 10 to 15 wt % of the second polymer component, andfrom 75 to 97 wt % of the first polymer component, or from 80 to 95 wt %of the first polymer component, or from 82 to 93 wt % of the firstpolymer component, or from 85 to 90 wt % of the first polymer component,based on the weight of the PBE, where desirable ranges may includeranges from any lower limit to any upper limit.

Preparation of Propylene-Based Elastomers

Polymerization of the PBE is conducted by reacting monomers in thepresence of a catalyst system described herein at a temperature of from0° C. to 200° C. for a time of from 1 second to 10 hours. Preferably,homogeneous conditions are used, such as a continuous solution processor a bulk polymerization process with excess monomer used as diluent.The continuous process may use some form of agitation to reduceconcentration differences in the reactor and maintain steady statepolymerization conditions. The heat of the polymerization reaction ispreferably removed by cooling of the polymerization feed and allowingthe polymerization to heat up to the polymerization, although internalcooling systems may be used.

Further description of exemplary methods suitable for preparation of thePBEs described herein may be found in U.S. Pat. Nos. 6,881,800;7,803,876; 8,013,069; and 8,026,323.

The triad tacticity and tacticity index of the PBE may be controlled bythe catalyst, which influences the stereoregularity of propyleneplacement, the polymerization temperature, according to whichstereoregularity can be reduced by increasing the temperature, and bythe type and amount of a comonomer, which tends to reduce the level oflonger propylene derived sequences.

Too much comonomer may reduce the crystallinity provided by thecrystallization of stereoregular propylene derived sequences to thepoint where the material lacks strength; too little and the material maybe too crystalline. The comonomer content and sequence distribution ofthe polymers can be measured using ¹³C nuclear magnetic resonance (NMR)by methods well known to those skilled in the art. Comonomer content ofdiscrete molecular weight ranges can be measured using methods wellknown to those skilled in the art, including Fourier Transform InfraredSpectroscopy (FTIR) in conjunction with samples by GPC, as described inWheeler and Willis, Applied Spectroscopy, 1993, Vol. 47, pp. 1128-1130.For a propylene ethylene copolymer containing greater than 75 wt %propylene, the comonomer content (ethylene content) of such a polymercan be measured as follows: A thin homogeneous film is pressed at atemperature of about 150° C. or greater, and mounted on a Perkin ElmerPE 1760 infrared spectrophotometer. A full spectrum of the sample from600 cm-1 to 4000 cm-1 is recorded and the monomer weight percent ofethylene can be calculated according to the following equation: Ethylenewt %=82.585−111.987X+30.045X2, where X is the ratio of the peak heightat 1155 cm-1 and peak height at either 722 cm-1 or 732 cm-1, whicheveris higher. For propylene ethylene copolymers having 75 wt % or lesspropylene content, the comonomer (ethylene) content can be measuredusing the procedure described in Wheeler and Willis. Reference is madeto U.S. Pat. No. 6,525,157, whose test methods are also fully applicablefor the various measurements referred to in this specification andclaims and which contains more details on GPC measurements, thedetermination of ethylene content by NMR and the DSC measurements.

The catalyst may also control the stereoregularity in combination withthe comonomer and the polymerization temperature. The PBEs describedherein are prepared using one or more catalyst systems. As used herein,a “catalyst system” comprises at least a transition metal compound, alsoreferred to as catalyst precursor, and an activator. Contacting thetransition metal compound (catalyst precursor) and the activator insolution upstream of the polymerization reactor or in the polymerizationreactor of the disclosed processes yields the catalytically activecomponent (catalyst) of the catalyst system. Such catalyst systems mayoptionally include impurity scavengers.

The catalyst systems used for producing the PBE may comprise ametallocene compound. In some embodiments, the metallocene compound is abridged bisindenyl metallocene having the general formula(In¹)Y(In²)MX₂, where In¹ and In² are (preferably identical) substitutedor unsubstituted indenyl groups bound to M and bridged by Y, Y is abridging group in which the number of atoms in the direct chainconnecting In¹ with In² is from 1 to 8 and the direct chain comprises Cor Si, and M is a Group 3, 4, 5, or 6 transition metal. In¹ and In² maybe substituted or unsubstituted. If In¹ and In² are substituted by oneor more substituents, the substituents are selected from the groupconsisting of a halogen atom, C₁ to C₁₀ alkyl, C₅ to C₁₅ aryl, C₆ to C₂₅alkylaryl, and N- or P-containing alkyl or aryl. Exemplary metallocenecompounds include, but are not limited to,μ-dimethyl-silylbis(indenyl)hafniumdimethyl andμ-dimethylsilylbis(indenyl)zirconiumdimethyl, and in particular(μ-dimethyl-silyl)bis(2-methyl-4-(3,′5′-di-tert-butylphenyl)indenyl)zirconiumdimethyl,(μ-dimethyl-silyl)bis(2-methyl-4-(3,′5′-di-tert-butylphenyl)indenyl)hafniumdimethyl,(μ-dimethyl-silyl)bis(2-methyl-4-naphthylindenyl)zirconiumdimethyl,(μ-dimethylsilyl)bis(2-methyl-4-naphthylindenyl)hafniumdimethyl,(μ-dimethylsilyl)bis(2-methyl-4-(N-carbazyl)indenyl)-zirconiumdimethyl,and(μ-dimethylsilyl)bis(2-methyl-4-(N-carbazyl)indenyl)-hafniumdimethyl.

Alternatively, the metallocene compound may correspond to one or more ofthe formulas disclosed in U.S. Pat. No. 7,601,666. Such metallocenecompounds include, but are not limited to, dimethylsilylbis(2-(methyl)-5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenz(f)indenyl)hafniumdimethyl, diphenylsilylbis(2-(methyl)-5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenz(f)indenyl)-hafniumdimethyl, diphenylsilylbis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenz(f)indenyl)-hafniumdimethyl, diphenylsilylbis(2-(methyl)-5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenz(f)indenyl)zirconium dichloride, and cyclo-propylsilylbis(2-(methyl)-5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenz(f)indenyl)hafnium dimethyl.

The activators of the catalyst systems used to produce PBE may comprisea cationic component. In some embodiments, the cationic component hasthe formula [R¹R²R³AH]⁺, where A is nitrogen, R¹ and R² are together a—(CH₂)_(a)— group, where a is 3, 4, 5 or 6, and form, together with thenitrogen atom, a 4-, 5-, 6- or 7-membered non-aromatic ring to which,via adjacent ring carbon atoms, optionally, one or more aromatic orheteroaromatic rings may be fused, and R³ is C₁, C₂, C₃, C₄ or C₅ alkyl,or N-methylpyrrolidinium or N-methylpiperidinium. In other embodiments,the cationic component has the formula [R_(n)AH]⁺, where A is nitrogen,n is 2 or 3, and all R are identical and are C₁ to C₃ alkyl groups, suchas, for example, trimethylammonium, trimethylanilinium,triethylammonium, dimethylanilinium, or dimethylammonium.

In one or more embodiments, the activators of the catalyst systems usedto produce the propylene-based polymer compositions comprise an anioniccomponent, [Y]⁻. In some embodiments, the anionic component is anon-coordinating anion (NCA), having the formula [B(R⁴)₄]⁻, where R⁴ isan aryl group or a substituted aryl group, of which the one or moresubstituents are identical or different and are selected from the groupconsisting of alkyl, aryl, a halogen atom, halogenated aryl, andhaloalkylaryl groups. In one or more embodiments, the substituents areperhalogenated aryl groups, or perfluorinated aryl groups, including butnot limited to perfluorophenyl, perfluoronaphthyl and perfluorobiphenyl.

Together, the cationic and anionic components of the catalysts systemsdescribed herein form an activator compound. In one or more embodimentsof the present invention, the activator may beN,N-dimethylanilinium-tetra(perfluorophenyl)borate,N,N-dimethylanilinium-tetra(perfluoronaphthyl)borate,N,N-dimethylanilinium-tetrakis(perfluoro-biphenyl)borate,N,N-dimethylanilinium-tetrakis(3,5-bis(trifluoromethyl)phenyl)borate,triphenylcarbenium-tetra(perfluorophenyl)borate,triphenylcarbenium-tetra(perfluoro-naphthyl)borate,triphenylcarbenium-tetrakis(perfluorobiphenyl)borate, ortriphenylcarbenium-tetrakis(3,5-bis(trifluoromethyl)phenyl)borate.

Any catalyst system resulting from any combination of a metallocenecompound, a cationic activator component, and an anionic activatorcomponent mentioned in the preceding paragraphs shall be considered tobe explicitly disclosed herein and may be used in accordance with thepresent invention in the polymerization of one or more olefin monomers.Also, combinations of two different activators can be used with the sameor different metallocene(s).

Further, the catalyst systems may contain, in addition to the transitionmetal compound and the activator described above, additional activators(co-activators) and/or scavengers. A co-activator is a compound capableof reacting with the transition metal complex, such that when used incombination with an activator, an active catalyst is formed.Co-activators include alumoxanes and aluminum alkyls.

In some embodiments, scavengers may be used to “clean” the reaction ofany poisons that would otherwise react with the catalyst and deactivateit. Typical aluminum or boron alkyl components useful as scavengers arerepresented by the general formula R^(x)JZ₂ where J is aluminum orboron, R^(x) is a C₁-C₂₀ alkyl radical, for example, methyl, ethyl,propyl, butyl, pentyl, and isomers thereof, and each Z is independentlyR^(x) or a different univalent anionic ligand such as halogen (Cl, Br,I), alkoxide (OR^(x)) and the like. Exemplary aluminum alkyls includetriethylaluminum, diethylaluminum chloride, ethylaluminum dichloride,tri-iso-butylaluminum, tri-n-octylaluminum, tri-n-hexylaluminum,trimethylaluminum and combinations thereof. Exemplary boron alkylsinclude triethylboron. Scavenging compounds may also be alumoxanes andmodified alumoxanes including methylalumoxane and modifiedmethylalumoxane.

Polymer Blends

Polymer blends according to the present invention may comprise at leastone ICP and at least one PBE. The blend may comprise from about 30 toabout 85 wt % ICP, or from about 40 to about 80 wt % ICP, or from about45 to about 80 wt % ICP, or from about 45 to about 75 wt % ICP, or fromabout 45 to about 70 wt % ICP, or from about 50 to about 65 wt % ICP,where desirable ranges may include ranges from any lower limit to anyupper limit. The blends may comprise from about 15 to about 70 wt % PBE,or from about 20 to about 60 wt % PBE, or from about 20 to about 55 wt %PBE, or from about 25 to about 55 wt % PBE, or from about 30 to about 55wt % PBE, or from about 35 to about 50 wt % PBE, where desirable rangesmay include ranges from any lower limit to any upper limit. Stateddifferently, the blends may comprise greater than about 10 wt % PBE, orgreater than about 15 wt % PBE, or greater than about 20 wt % PBE, orgreater than about 25 wt % PBE, or greater than about 30 wt % PBE, orgreater than about 35 wt % PBE.

A variety of additives may be incorporated into the polymer blendsdescribed herein, depending upon the intended purpose. For example, whenthe blends are used to form fibers and nonwoven fabrics, such additivesmay include, but are not limited to stabilizers, antioxidants, fillers,colorants, nucleating agents, dispersing agents, mold release agents,slip agents, fire retardants, plasticizers, pigments, vulcanizing orcurative agents, vulcanizing or curative accelerators, cure retarders,processing aids, tackifying resins, and the like. Other additives mayinclude fillers and/or reinforcing materials, such as carbon black,clay, talc, calcium carbonate, mica, silica, silicate, combinationsthereof, and the like. Primary and secondary antioxidants include, forexample, hindered phenols, hindered amines, and phosphates. Nucleatingagents include, for example, sodium benzoate and talc. Also, to improvecrystallization rates, other nucleating agents may also be employed suchas Ziegler-Natta olefin products or other highly crystalline polymers.Other additives such as dispersing agents, for example, Acrowax C, canalso be included. Slip agents include, for example, oleamide anderucamide. Catalyst deactivators are also commonly used, for example,calcium stearate, hydrotalcite, and calcium oxide, and/or other acidneutralizers known in the art.

Further, in some exemplary embodiments, additives may be incorporatedinto the polymer blends directly or as part of a masterbatch, i.e., anadditive package containing several additives to be added at one time inpredetermined proportions. In one or more embodiments herein, the fiberof the present invention further comprise a masterbatch comprising aslip agent. The masterbatch may be added in any suitable amount toaccomplish the desired result. For example, a masterbatch comprising aslip additive may be used in an amount ranging from about 0.1 to about10 wt %, or from about 0.25 to about 7.5 wt %, or from about 0.5 toabout 5 wt %, or from about 1 to about 5 wt %, or from about 2 to about4 wt %, based on the total weight of the polymer blend and themasterbatch. In an embodiment, the masterbatch comprises erucamide asthe slip additive.

Fibers, Nonwoven Compositions, and Laminates Prepared from PolymerBlends

The polymer blends described herein are particularly useful in meltspun(e.g., meltblown or spunbond) fibers and nonwoven compositions (e.g.,fabrics). As used herein, “meltspun nonwoven composition” refers to acomposition having at least one meltspun layer, and does not requirethat the entire composition be meltspun or nonwoven. In someembodiments, the nonwoven compositions additionally comprise one or morelayers positioned on one or both sides of the nonwoven layer(s)comprising the polymer blend. As used herein, “nonwoven” refers to atextile material that has been produced by methods other than weaving.In nonwoven fabrics, the fibers are processed directly into a planarsheet-like fabric structure and then are either bonded chemically,thermally, or interlocked mechanically (or both) to achieve a cohesivefabric.

The present invention is directed not only to fibers and nonwovencompositions, but also to processes for forming nonwoven compositionscomprising the polymer blends described herein. In one or moreembodiments, such methods comprise the steps of forming a molten polymercomposition comprising a blend of at least one ICP and at least one PBEas described above, and forming fibers comprising the polymer blend. Insome embodiments, the methods further comprise forming a nonwovencomposition from the fibers.

In some embodiments, the nonwoven composition formed from the ICP/PBEblend is employed as a facing layer. The process may then furthercomprise the steps of forming the facing layer, and then forming anonwoven elastic layer on the facing layer. For example, the nonwovenelastic layer may be formed by meltspinning or meltblowing a layer ofmolten polymer onto the facing layer. Optionally, an additional facinglayer may then be disposed upon the opposite side of the elastic layer,such that the elastic layer is sandwiched between the facing layers. Inone or more embodiments, the elastic layer or layers may comprise a PBEhaving the composition and properties described above.

In certain embodiments, nonwoven compositions comprising the ICP/PBEblends may be described as extensible. “Extensible,” as used herein,means any fiber or nonwoven composition that yields or deforms (i.e.,stretches) upon application of a force. While many extensible materialsare also elastic, the term extensible also encompasses those materialsthat remain extended or deformed upon removal of the force. Fabriclayers containing the blends described herein are useful as extensiblefacing layers in combination with an elastic core layer, which may be afilm or a nonwoven layer. When an extensible facing layer is used incombination with an elastic core layer, the extensible layer maypermanently deform when the elastic layer to which it is attachedstretches and retracts, creating a wrinkled or textured outer surfacewhich gives an additional soft feel that is particularly suited forarticles in which the facing layer is in contact with a wearer's skin.

The fibers and nonwoven compositions of the present invention can beformed by any method known in the art. For example, the nonwovencompositions may be produced by a spunmelt process. In certainembodiments herein, the layer or layers of the nonwoven compositions ofthe invention are produced by a spunbond process. When the compositionsfurther comprise one or more elastic layers, the elastic layers may beproduced by a meltblown process, by a spunbond or spunlace process, orby any other suitable nonwoven process.

Fibers produced from the ICP/PBE blend may have a thickness from about0.5 to about 10 denier, or from about 0.75 to about 8 denier, or fromabout 1 to about 6 denier, or from about 1 to about 3 denier, wheredesirable ranges may include ranges from any lower limit to any upperlimit. Although commonly referred to in the art and used herein forconvenience as an indicator of thickness, denier is more accuratelydescribed as the linear mass density of a fiber. A denier is the mass(in grams) of a fiber per 9,000 meters. In practice, measuring 9,000meters may be both time-consuming and wasteful. Usually, a sample oflesser length (i.e., 900 meters, 90 meters, or any other suitablelength) is weighed and the result multiplied by the appropriate factorto obtain the denier of the fiber.

The fiber denier (g/9000 m) of a polypropylene-based fiber can beconverted to diameter in microns using the following formula:

$D = \sqrt[2]{\frac{denier}{(0.006432)}}$

Thus, a 1.0 denier polypropylene fiber would have a diameter of about12.5 micron and a 2.0 denier polypropylene fiber would have a diameterof 17.6 micron.

In some embodiments, fibers produced from the ICP/PBE blend may have athickness/diameter of from about 5 to 50 μm, or from about 15 to 25 μm,or from about 10 to 20 μm, where desirable ranges may include rangesfrom any lower limit to any upper limit.

The fibers may be monocomponent fibers or bicomponent fibers.Preferably, the fibers are monocomponent fibers, meaning that the fibershave a consistent composition throughout their cross-section.

The nonwoven layer or layers described herein may be composed primarilyof a blend of an ICP and a PBE as described previously. In someembodiments, the layer that comprises the blend may have a basis weightof less than 50 g/m² (“gsm”), or less than 40 gsm, or less than 30 gsm,or less than 25 gsm, or less than 20 gsm. The layer that comprises theblend may have a basis weight of from about 1 to about 75 g/m² (“gsm”),or from about 2 to about 50 gsm, or from about 5 to about 35 gsm, orfrom about 7 to about 25 gsm, or from about 10 to about 25 gsm, wheredesirable ranges may include ranges from any lower limit to any upperlimit.

The nonwoven layer that comprises the blend of the ICP and the PBE mayhave a tensile strength in the machine direction (MD) from about 5 toabout 65 N/5 cm, or from about 7 to about 60 N/5 cm, or from about 10 toabout 55 N/5 cm, or from about 10 to about 50 N/5 cm, or from about 15to about 45 N/5 cm, where desirable ranges may include ranges from anylower limit to any upper limit. Stated differently, the nonwovens mayhave an MD tensile strength greater than about 5 N/5 cm, or greater thanabout 10 N/5 cm, or greater than about 15 N/5 cm, or greater than about20 N/5 cm. In the same or other embodiments, the nonwovens may have atensile strength in the cross direction (CD) from about 5 to about 55N/5 cm, or from about 7 to about 50 N/5 cm, or from about 10 to about 45N/5 cm, or from about 10 to about 40 N/5 cm, or from about 15 to about35 N/5 cm, where desirable ranges may include ranges from any lowerlimit to any upper limit. Stated differently, the nonwovens may have anMD tensile strength greater than about 5 N/5 cm, or greater than about10 N/5 cm, or greater than about 15 N/5 cm, or greater than about 20 N/5cm. Tensile strength of the fabric is determined in accordance withWSP110.4 (05) using the EDANA ERT 20.2-89 Option B.

The nonwoven layer that comprises the blend of the ICP and the PBE mayhave a peak elongation in the machine direction (MD) greater than about70%, or greater than about 75%, or greater than about 80%, or greaterthan about 85%, or greater than about 90%, or greater than about 95%, orgreater than about 100%, or greater than about 120%, or greater thanabout 150%. The nonwoven layer may have a peak elongation in the crossdirection (CD) greater than about 100%, or greater than about 110%, orgreater than about 115%, or greater than about 120%, or greater than150%, or greater than 200%. Elongation of the fabric is determined inaccordance with WSP110.4 (05) using the EDANA ERT 20.2-89 Option B.

In some embodiments, fibers made with the ICP/PBE blend may have a peakelongation of greater than 150%, or greater than 200%, or greater than225%, or greater than 250%, or greater than 275%, or greater than 300%,or greater than 325%, or greater than 350%, when spun at 1500 m/min. Thefiber peak elongation may be measured using a Textechno Statimat Mloaded with a Textechno program FPAM0210E. These Textechno products arecommercially available from Textechno Herbert Stein GmbH & Co., locatedin Mönchengladbach, Germany. To test the fibers, the fiber is threadedthrough the ceramic guides on the Statimat M into a pneumatic clamp. Thegage length for the fiber being tested is 100 mm. The fiber is pulled at1270 mm/min until it failed. The force to pull the fiber and the strainof the fiber bundle were recorded until the failure occurred. The “peakelongation” is the elongation at which the maximum force is observed.Five fiber samples are tested and the average is reported.

In some embodiments, fibers made with the ICP/PBE blend may haveimproved spinability as illustrated by the speed to break. For example,the fibers may have a speed to break of greater than 2000 m/min, orgreater than 2500 m/min, or greater than 3000 m/min, or greater than3500 m/min, or greater than 4000 m/min. The “speed to break” may bedetermined by slowly increasing the spinning speed on the fiber spinningmachine in 25 m/min increments until the fiber breaks. This is repeatedthree times and the average value is reported.

In addition to good extensibility and elongation, fibers comprising theblends described herein may also be used to produce fabrics that haveimproved aesthetics. For example, the fabrics may have an improved feeland softness. Without being bound by theory, it is believed that fabricsproduced using the blends described herein have lower bending modulus,due to lower crystallinity, which improves the softness or feel of thefabric. Fabrics made from fibers comprising the blends described hereinmay have improved softness, as measured by a Handle-O-Meter.

In certain embodiments, a 35 g/m² facing layer comprising the blendsdescribed herein has a Handle-O-Meter value of less than 60 g, or lessthan 50 g, or less than 40 g. The softness of a nonwoven fabric may bemeasured according to the “Handle-O-Meter” test as specified in theoperating manual on Handle-O-Meter model number 211-5 from theThwing-Albert Instrument Co. The Handle-O-Meter reading is in units ofgrams. The modifications were: (1) two specimens per sample were used;and (2) readings were kept below 100 gram by adjusting the slot widthused and the same slot width was used throughout the whole series ofsamples being compared. The Handle-O-Meter values used throughout havean error of ±25% of the reported value.

As used herein, “meltblown fibers” and “meltblown compositions” (or“meltblown fabrics”) refer to fibers formed by extruding a moltenthermoplastic material at a certain processing temperature through aplurality of fine, usually circular, die capillaries as molten threadsor filaments into high velocity, usually hot, gas streams whichattenuate the filaments of molten thermoplastic material to reduce theirdiameter, which may be to microfiber diameter. Thereafter, the meltblownfibers are carried by the high velocity gas stream and are deposited ona collecting surface to form a web or nonwoven fabric of randomlydispersed meltblown fibers. Such a process is generally described in,for example, U.S. Pat. Nos. 3,849,241 and 6,268,203. The termmeltblowing as used herein is meant to encompass the meltspray process.

Commercial meltblown processes utilize extrusion systems having arelatively high throughput, in excess of 0.3 grams per hole per minute(“ghm”), or in excess of 0.4 ghm, or in excess of 0.5 ghm, or in excessof 0.6 ghm, or in excess of 0.7 ghm. The nonwoven compositions of thepresent invention may be produced using commercial meltblown processes,preferably a high pressure meltblown process available fromBiax-Fiberfilm Corporation, or in test or pilot scale processes. In oneor more embodiments of the present invention, the fibers used to formthe nonwoven compositions are formed using an extrusion system having athroughput rate of from about 0.01 to about 3.0 ghm, or from about 0.1to about 2.0 ghm, or from about 0.3 to about 1.0 ghm.

In a typical spunbond process, polymer is supplied to a heated extruderto melt and homogenize the polymers. The extruder supplies meltedpolymer to a spinneret where the polymer is fiberized as passed throughfine openings arranged in one or more rows in the spinneret, forming acurtain of filaments. The filaments are usually quenched with air at alow temperature, drawn, usually pneumatically, and deposited on a movingmat, belt or “forming wire” to form the nonwoven composition. See, forexample, in U.S. Pat. Nos. 4,340,563; 3,692,618; 3,802,817; 3,338,992;3,341,394; 3,502,763; and 3,542,615. The term spunbond as used herein ismeant to include spunlace processes, in which the filaments areentangled to form a web using high-speed jets of water (known as“hydroentanglement”).

The nonwoven layer that comprises the blend of the ICP and the PBEdescribed herein may be a single layer, or may be part of a multilayerlaminate. One application is to make a laminate (or “composite”) frommeltblown (“M”) and spunbond (“S”) nonwoven compositions, which combinesthe advantages of strength from the spunbonded component and greaterbarrier properties of the meltblown component. In such applications, thenonwoven layer that comprises the blend of the ICP and the PBE may beparticularly useful as an outer spunbond layer. A typical laminate orcomposite has three or more layers, a meltblown layer(s) sandwichedbetween two or more spunbonded layers, or “SMS” nonwoven composites.Examples of other combinations are SSMMSS, SMMS, and SMMSS composites.Composites can also be made of the meltblown or spunbond nonwovens ofthe invention with other materials, either synthetic or natural, toproduce useful articles.

In certain embodiments, a nonwoven laminate composition may comprise oneor more elastic layers comprising a PBE and further comprise one or morefacing layers comprising the ICP/PBE blend as described hereinpositioned on one or both sides of the elastic layer(s). In someembodiments, the elastic layers and the facing layers may be produced ina single integrated process, preferably a continuous process. Forexample, a spunmelt process line may incorporate meltblown technologysuch that multilayer nonwoven laminates are produced that contain one ormore meltblown elastic layers laminated to one or more other spunbondlayers (which may be elastic or inelastic) in a single continuousintegrated process.

The nonwoven products described above may be used in many articles suchas hygiene products including, but not limited to, diapers, femininecare products, and adult incontinent products. The nonwoven products maybe useful in diaper applications, and may be particularly useful in theelastic ear of the diaper. The nonwoven products may also be used inmedical products such as sterile wrap, isolation gowns, operating roomgowns, surgical gowns, surgical drapes, first aid dressings, and otherdisposable items. In particular, the nonwoven products may be useful asfacing layers for medical gowns, and allow for extensibility in theelbow area of the gown. The nonwoven products may also be useful indisposable protective clothing, and may add toughness to elbow and kneeregions of such clothing. The nonwoven products may also be useful asprotective wrapping, packaging or wound care. The nonwoven products mayalso be useful in geotextile applications, as the fabric may haveimproved puncture resistance in that the fabric will deform instead ofpuncture.

Examples

In order to provide a better understanding of the foregoing discussion,the following non-limiting examples are offered. Although the examplesmay be directed to specific embodiments, they are not to be viewed aslimiting the invention in any specific respect. All parts, proportions,and percentages are by weight unless otherwise indicated.

The following test methods were used in the Examples.

The melt flow rate (MFR) of the polymer samples was measured accordingto ASTM D-1238, Condition L, at 230° C. using a 2.16 kg load. The MFR isreported in “g/10 min”.

The MWD distribution was measured by GPC as described above.

The intrinsic viscosity (IV) was measured according to ASTM D1601standard, using a decalin solvent at 135° C. The IV is reported in“dl/g”.

Fiber elongation and tenacity were measured using a Textechno Statimat Mloaded with a Textechno program FPAM0210E. These Textechno products arecommercially available from Textechno Herbert Stein GmbH & Co. locatedin Mönchengladbach, Germany. To test the fibers, the fiber bundle wasthreaded through ceramic guides on the Statimat M into a pneumaticclamp. The gage length for the fiber bundles being tested is 100 mm.

The tenacity and peak elongation were determined using the TextechnoStatimat machine. Each fiber bundle was pulled at 1270 mm/min until itfailed. The force to pull the fiber bundle and the strain of the fiberbundle were recorded until the failure occurred. The “tenacity” is theforce/denier of the fiber bundle (72-fibers per bundle) and is reportedin grams/denier. The “peak elongation” is the elongation at which themaximum force is observed. The “elongation at break” is defined as theelongation at which the measured force drops to 90% of the maximum valueor the point at which the fiber bundle breaks, whichever comes first.Five fiber bundle samples are tested and the average is reported.

The ICPs identified in Table 1 were used in the examples. Each ICP usedwas a reactor blend of a polypropylene homopolymer component (ComponentA) and an ethylene-propylene copolymer component (Component B). The “ICPMFR” is the MFR of the ICP. The “Comp. A MFR” is the MFR of thepolypropylene homopolymer component (Component A) of the ICP. The “Comp.A MWD” is the MWD of the polypropylene homopolymer component (ComponentA) of the ICP. The “Comp. B wt %” is the weight percent of theethylene-propylene copolymer component (Component B) in the ICP, and isbased on the total weight of the ICP. The “Comp. B C₂ Content” is theethylene content of the ethylene-propylene copolymer component(Component B), and is based on the weight of Component B. The “ICP C₂Content” is the total ethylene content of the ICP and is based on theweight of the ICP.

TABLE 1 ICP Compositions Comp. B C₂ ICP C₂ ICP ICP Comp. A Comp. A Comp.B Content Content Sample # MFR MFR MWD wt % (wt %) (wt %) A ~35 ~50 ~3.821.0 52 10.9 B 30 145 4 26.0 56 14.6 C 30 145 4 26.0 56 14.6 D 32 155 426.6 45 12.0 E 29.5 160 ~4 26.1 38 9.8 F ~30 157 ~4 25.8 38 9.8 G 30-40~65 ~4 ~8.5 ~46 ~3.9

The PBEs identified in Table 2 were used in the examples. Each PBE usedwas a reactor blended polymer of a first polymer component and a secondpolymer component made in parallel solution polymerization reactors. The“1^(st) Comp. C₂ Content” is the ethylene content of the first polymercomponent, based upon the total weight of the propylene-derived andethylene derived units of the first polymer component. The “2^(nd) Comp.C₂ Content” is the ethylene content of the second polymer component,based upon the total weight of the propylene-derived and ethylenederived units of the second polymer component. The “Total C₂ Content” isthe ethylene content of the PBE, where the percentage by weight is basedupon the total weight of the propylene-derived and ethylene derivedunits of the PBE. The “polysplit” is the weight percentage of the secondpolymer component, based on the weight of the PBE. The “PBE MWD” is themolecular weight distribution of the PBE. The “PBE MFR” is the melt flowrate of the PBE.

TABLE 2 PBE Compositions 1^(st) Comp. 2^(nd) Comp. Total C₂ C₂ C₂ PBEContent Content Content PBE PBE Sample # (wt %) (wt %) (wt %) PolysplitMWD MFR X 16 4 14.5 10 2 20 Y 16-17 3-4 16.0 10 2 3 Z 14.1 8.4 13.1 10 253

Example 1

Fibers were made from polymer blends of an ICP and a PBE were preparedas shown in Table 3. The ICP and the PBE were melt blended togetherin-line with the fiber spinning machine. In addition to Blend Samples1-12, fibers were also formed from a comparative material, identified asC1. C1 comprised 100 wt % propylene homopolymer with a MWD of about 3that is commercially available from ExxonMobil Chemical Co. as PP3155.

TABLE 3 Polymer Blends Blend Est. Blend Sample No. ICP ICP, Wt % PBEPBE, Wt % MFR 1 A 54 X 46 27 2 A 54 Z 46 42 3 A 60 Z 40 41 4 B 54 X 4625 5 B 54 Z 46 39 6 B 60 Z 40 37 7 C 54 X 46 25 8 C 54 Z 46 39 9 C 60 Z40 37 10 D 54 X 46 26 11 D 54 Z 46 40 12 D 60 Z 40 39

The fibers were partially oriented yarn fibers produced on continuousfilament spinning equipment. The fiber spinning machine is commerciallyavailable from Hills, Inc., located in West Melbourne, Fla. The fiberspinning machine is of lab scale size with a 2 inch single screwextruder. The spinnerette has 72 capillaries. Each capillary diameterwas 0.6 mm. The fibers were spun at a melt temperature of 450° F. (232°C.) and a throughput of 0.6 ghm. Fibers were made at three differentspin speeds, 1500 m/min, 2000 m/min, and 2500 m/min. These fiber bundleswere collected on a spool, with each fiber bundle containing 72 fibers.

The “speed to break” was then determined by slowly increasing thespinning speed in 25 m/min increments until the fiber bundle breaks.This is repeated three times and the average value is reported. Themechanical maximum spinning speed capability for the machine is 5000m/min.

The properties of the resulting fiber bundles are shown in Table 4,below. The “Speed to Break” is the maximum spinning speed when the fiberfailed/broke and is reported in m/min. The “Pk Elng (1500)”, “Pk Elng(2000)”, and “Pk Elng (2500)” are the peak elongations of the fibers(elongation to break) that were produced at a spinning speed of 1500m/min, 2000 m/min, and 2500 m/min, respectively. The peak elongation isreported in %. The “Ten (1500)”, “Ten (2000)”, and “Ten (2500)” are thetenacity of the fibers that were produced at a spinning speed of 1500m/min, 2000 m/min, and 2500 m/min, respectively. The tenacity isreported in g/denier. The “Denier (1500)”, “Denier (2000)”, and “Denier(2500)” are the deniers of the fibers that were produced at a spinningspeed of 1500 m/min, 2000 m/min, and 2500 m/min, respectively.

TABLE 4 Fiber Properties Speed to Break Pk Elng Pk Elng Pk Elng Ten TenTen Denier Denier Denier Sample # (m/min) (1500) (2000) (2500) (1500)(2000) (2500) (1500) (2000) (2500) C1 5000 205.5 194.5 174 1.99/ 1.99/2.43 251 189 151 2.21 2.21 1 3750 148 135 113 1.69/ 2.04 2.24/ 260 190150 165 2.11 2 3850 194 143 115 1.59 1.74 1.65 260 190 160 3 2700 164145.5 112 1.52 1.76/ 2.07 250 190 150 1.76 4 225 181 135 — 1.41 1.91/ —260 190 — 1.71 5 2350 183 123 — 1.29 1.42 — 251 193 — 6 2800 184 152 1161.25 1.32 1.40/ 254 195 156 1.57 7 1850 149 — — 1.09/ — — 244 — — 1.11 84300 182 157 110 1.32/ 1.48 1.69/1.55 258 194 163 1.35 9 1850 171.5 — —1.12/ — — 244 — — 1.09 10 3000 198 183 131 1.56/ 1.87 1.82/ 252 194 1631.58 1.84 11 4400 245 182 149.5 1.35 1.70/ 1.70/ 253 194 153 1.69 1.7712 4600 247.5 221 141.5 1.27/ 1.56 1.68/ 262 190 156 1.25 1.69

As reflected in Table 4 and FIG. 1, blending a PBE with a high MFR andan ICP with a lower ethylene content copolymer component resulted infibers having high peak elongations.

Example 2

Fibers were made from polymer blends of an ICP and a PBE were preparedas shown in Table 5. The ICP and the PBE were first dry blendedtogether, and then melt mixed in an extruder and pelletized.

TABLE 5 Polymer Blends of Example 2 Blend Sample No. ICP ICP, Wt % PBEPBE, Wt % 13 A 55 X 45 14 D 55 X 45 15 A 55 Z 45 16 A 45 Z 55 17 A 35 Z65 18 D 55 Z 45 19 D 45 Z 55 20 D 35 Z 65

The pelletized blends were then used to form fibers, as described abovein Example 1. In addition to Blend Samples 12-19, fibers were alsoformed from a comparative material, identified as C1. C1 comprised 100wt % propylene homopolymer commercially available from ExxonMobilChemical Co. as PP3155. The properties of the resulting fiber bundlesare reported in Table 6.

TABLE 6 Fiber Properties of Example 2 Speed to Break Pk Elng Pk Elng PkElng Ten Ten Ten Denier Denier Denier Sample # (m/min) (1500) (2000)(2500) (1500) (2000) (2500) (1500) (2000) (2500) C1 5000 230 211 169.52.27 2.35 2.40 256 192 156 13 4450 182 131 131 1.80 2.03 2.35 260 192156 14 3800 224 166.8 144 1.48 1.74 1.76 257 198 157 15 5000 168 148118.3 1.54 1.90 1.88 254 191 155 16 4600 167 138 106.2 1.64 1.90 1.90256 192 157 17 4300 140 112 99.7 1.69 1.84 2.04 249 191 158 18 3900 287225 154 1.24 1.46 1.77 254 196 156 19 4200 216.4 182 126 1.33 1.61 1.84263 196 156 20 4600 206 162 126 1.64 1.75 2.13 253 195 156

As reflected in Table 6 and FIG. 2, blending a PBE that had a high MFRand an ICP with a lower ethylene content copolymer component resulted infibers having high peak elongations and good spinability.

Example 3

Fibers were made from polymer blends of an ICP and a PBE were preparedas described above in Example 1. The polymer blend formulations areshown in Table 7.

Fibers were also formed from a comparative material, identified as Cl,which comprised 100 wt % propylene homopolymer commercially availablefrom ExxonMobil Chemical Co. as PP3155. The properties of the resultingfiber bundles are reported in Table 8.

TABLE 7 Polymer Blends of Example 3 Blend Sample No. ICP ICP, Wt % PBEPBE, Wt % 21 A 55 X 45 22 E 55 X 45 23 F 55 X 45 24 G 55 X 45 25 A 55 Z45 26 A 45 Z 55 27 A 35 Z 65 28 E 65 Z 35 29 E 55 Z 45 30 E 45 Z 55 31 E35 Z 65 32 F 65 Z 35 33 F 55 Z 45 34 F 45 Z 55 35 F 35 Z 65 36 G 65 Z 3537 G 55 Z 45 38 G 45 Z 55 39 G 35 Z 65

TABLE 8 Fiber Properties of Example 3 Max Speed to Break Pk Elng Pk ElngPk Elng Ten Ten Ten Denier Denier Denier Sample # (m/min) (1500) (2000)(2500) (1500) (2000) (2500) (1500) (2000) (2500) C1 5000 247 206 1822.29 2.16 2.41 247 193 155 21 3850 162 124 95 1.79 2.16 2.19 255 189 15522 3680 194 171 129 1.59 1.80 2.36 255 192 152 23 3550 242 176 171 1.651.76 1.98 265 199 159 24 3050 332 230 183 1.35 1.61 1.81 259 195 157 254150 200 151 116 1.81 1.85 2.17 253 189 158 26 4500 173 124 101 1.932.06 2.27 250 197 157 27 4750 160 117 95 2.02 2.01 2.25 251 195 153 284750 260 201 189 1.47 1.53 1.71 247 196 160 29 4650 222 199 147 1.441.64 2.01 261 195 160 30 5000 222 177 146 1.49 1.86 1.45 260 195 157 315000 186 158 135 1.53 1.81 2.19 263 196 154 32 3900 268 214 175 1.261.43 1.65 258 193 157 33 4050 235 195 201 1.31 1.71 2.02 259 193 155 344400 244 183 159 1.54 1.68 1.93 254 192 159 35 4550 209 156 137 1.551.77 2.12 255 196 156 36 2750 380 283 239 1.26 1.38 1.72 249 193 158 372650 322 392 194 1.22 1.48 1.75 258 194 155 38 3350 311 213 188 1.181.54 1.75 262 188 162 39 4100 279 219 166 1.26 1.58 1.63 263 193 155

As reflected in Table 8 and FIG. 3, blending a PBE that had a high MFRand an ICP with a lower ethylene content copolymer component resulted infibers having high peak elongations and good spinability.

For purposes of convenience, various specific test procedures areidentified above for determining certain properties. However, when aperson of ordinary skill reads this patent and wishes to determinewhether a composition or polymer has a particular property identified ina claim, then any published or well-recognized method or test procedurecan be followed to determine that property, although the specificallyidentified procedure is preferred. Each claim should be construed tocover the results of any of such procedures, even to the extentdifferent procedures can yield different results or measurements. Thus,a person of ordinary skill in the art is to expect experimentalvariations in measured properties that are reflected in the claims.

Having described the various aspects of the compositions herein, furtherspecific embodiments of the invention include those set forth in thefollowing paragraphs.

Embodiment A

A fiber comprising a blend of from about 30 to about 85 wt % of animpact copolymer and from about 15 to about 70 wt % of a propylene-basedelastomer,

wherein the impact copolymer is a reactor blend and comprises apropylene homopolymer component and a copolymer component, where thecopolymer component comprises less than 55 wt % ethylene-derived units,based on the weight of the copolymer component; and

wherein the propylene-based elastomer comprises propylene and from about5 to about 25 wt % units derived from one or more C₂ or C₄-C₁₂alpha-olefins and has an MFR of greater than about 20 g/10 min and aheat of fusion less than about 75 J/g.

Embodiment B

The fiber of Embodiment A, wherein the fiber comprises from about 20 toabout 70 wt % of the propylene-based elastomer.

Embodiment C

The fiber of Embodiment A or B, wherein the fiber comprises from about30 to about 65 wt % of the propylene-based elastomer.

Embodiment D

The fiber of any one of Embodiments A to C, wherein the fiber comprisesfrom about 45 to about 65 wt % of the propylene-based elastomer.

Embodiment E

The fiber of any one of Embodiments A to D, wherein the propylenehomopolymer component of the impact copolymer has a MFR of greater thanabout 100 g/10 min.

Embodiment F

The fiber of any one of Embodiments A to E, where the propylenehomopolymer component has a MFR of greater than 130 g/10 min.

Embodiment G

The fiber of any one of Embodiments A to F, where the propylenehomopolymer component has a MFR of greater than 140 g/10 min.

Embodiment H

The fiber of any one of Embodiments A to G, where the propylenehomopolymer component has a MFR of greater than 150 g/10 min.

Embodiment I

The fiber of any one of Embodiments A to H, where the propylenehomopolymer component has a MWD of from 1.0 to 7.0.

Embodiment J

The fiber of any one of Embodiments A to I, where the propylenehomopolymer component has a MWD of from 3.0 to 5.0.

Embodiment K

The fiber of any one of Embodiments A to J, where the copolymercomponent of the impact copolymer comprises from about 35 to about 55 wt% ethylene-derived units, based on the weight of the copolymercomponent.

Embodiment L

The fiber of any one of Embodiments A to K, where the copolymercomponent of the impact copolymer comprises from about 40 to about 52 wt% ethylene-derived units, based on the weight of the copolymercomponent.

Embodiment M

The fiber of any one of Embodiments A to L, where the copolymercomponent of the impact copolymer comprises from about 43 to about 50 wt% ethylene-derived units, based on the weight of the copolymercomponent.

Embodiment N

The fiber of any one of Embodiments A to M, where the impact copolymercomprises from about 40 to about 95 wt % of the propylene homopolymercomponent and from about 5 wt % to about 60 wt % of the copolymercomponent.

Embodiment O

The fiber of any one of Embodiments A to N, where the impact copolymercomprises from about 50 wt % to about 90 wt % of the propylenehomopolymer component and from about 10 to about 50 wt % of thecopolymer component.

Embodiment P

The fiber of any one of Embodiments A to O, where the impact copolymerhas an ethylene content of from about 3 wt % to about 40 wt %, based onthe weight of the impact copolymer.

Embodiment Q

The fiber of any one of Embodiments A to P, where the impact copolymerhas an ethylene content of from about 5 wt % to about 25 wt %, based onthe weight of the impact copolymer.

Embodiment R

The fiber of any one of Embodiments A to Q, where the propylene-basedelastomer is a reactor blend of a first polymer component and a secondpolymer component.

Embodiment S

The fiber of Embodiment R, where the first polymer component comprisespropylene and ethylene and has an ethylene content of greater than 10 wt%, based on the weight of the first polymer component.

Embodiment T

The fiber of Embodiment R or S, where the first polymer componentcomprises propylene and ethylene and has an ethylene content of fromabout 10 to about 20 wt %, based on the weight of the first polymercomponent.

Embodiment U

The fiber of any one of Embodiments R to T, where the second polymercomponent comprises propylene and ethylene and has an ethylene contentof greater than 2 wt %, based on the weight of the second polymercomponent.

Embodiment V

The fiber of any one of Embodiments R to U, where the second polymercomponent comprises propylene and ethylene and has an ethylene contentof from about 2 to about 10 wt %, based on the weight of the secondpolymer component.

Embodiment W

The fiber of any one of Embodiments R to V, where the propylene-basedelastomer comprises from 3-25 wt % of the second polymer component,based on the weight of the propylene-based elastomer.

Embodiment X

The fiber of any one of Embodiments A to W, further comprising a slipadditive.

Embodiment Y

The fiber of any one of Embodiments A to X, wherein the fiber has amonocomponent structure.

Embodiment Z

The fiber of any one of Embodiments A to Y, wherein the fiber has a peakelongation of greater than 150%.

Embodiment AA

The fiber of any one of Embodiments A to Z, wherein the fiber has a peakelongation of greater than 175%.

Embodiment AB

The fiber of any one of Embodiments A to AA, wherein the fiber has apeak elongation of greater than 200%.

Embodiment AC

A nonwoven composition comprising one or more fibers according to anyone of Embodiments A to AB.

Embodiment AD

A nonwoven composition comprising a blend of from about 30 to about 85wt % of an impact copolymer and from about 15 to about 70 wt % of apropylene-based elastomer,

wherein the impact copolymer is a reactor blend and comprises apropylene homopolymer component and a copolymer component, and where thecopolymer component comprises less than 55 wt % ethylene-derived units,based on the weight of the copolymer component; and

wherein the propylene-based elastomer comprises propylene and from about5 wt % to about 25 wt % units derived from one or more C₂ or C₄-C₁₂alpha-olefins and has a MFR of greater than about 20 g/10 min and a heatof fusion less than about 75 J/g.

Embodiment AE

The nonwoven composition of Embodiment AC or AD, where the compositionis spunbond.

Embodiment AF

The nonwoven composition of any one of Embodiments AC to AE, where thecomposition has a basis weight of less than 50 gsm.

Embodiment AG

The nonwoven composition of any one of Embodiments AC to AF, where thecomposition has a basis weight of less than 30 gsm.

Embodiment AH

The nonwoven composition of any one of Embodiments AC to AG, where thecomposition has a peak elongation in the cross direction (CD) greaterthan about 100%.

Embodiment AI

The nonwoven composition of any one of Embodiments AC to AH, where thecomposition has a peak elongation in the cross direction (CD) greaterthan about 150%.

Embodiment BA

A nonwoven laminate comprising an elastic layer and at least one facinglayer, wherein the facing layer comprises fibers according to any one ofEmbodiments A to AB.

Embodiment BB

A nonwoven laminate comprising an elastic layer and at least one facinglayer, wherein the facing layer comprises a nonwoven compositionaccording to any one of Embodiments AC through AI.

Embodiment BC

A nonwoven laminate comprising: (i) an elastic layer; and (ii) one ormore facing layers, wherein the facing layer comprises from about 30 toabout 85 wt % of an impact copolymer and from about 15 to about 70 wt %of a propylene-based elastomer,

wherein the impact copolymer is a reactor blend and comprises apropylene homopolymer component and a copolymer component, and where thecopolymer component comprises less than 55 wt % ethylene-derived units,based on the weight of the copolymer component; and

wherein the propylene-based elastomer comprises propylene and from about5 wt % to about 25 wt % units derived from one or more C₂ or C₄-C₁₂alpha-olefins and has a MFR of greater than about 20 g/10 min and a heatof fusion less than about 75 J/g.

Embodiment BD

The nonwoven laminate of any one of Embodiments BA to BC, wherein thefacing layer comprises from about 25 to about 50 wt % of thepropylene-based elastomer.

Embodiment BE

The nonwoven laminate of any one of Embodiments BA to BD, wherein thefacing layer further comprises from about 1 to about 5 wt % of amasterbatch comprising a slip additive.

Embodiment BF

The nonwoven laminate of any one of Embodiments BA to BE, wherein thefacing layer is formed from monocomponent fibers having a thickness fromabout 0.5 to about 10 denier.

Embodiment BG

The nonwoven laminate of any one of Embodiments BA to BF, wherein thefacing layer is a spunbond nonwoven fabric having a basis weight of lessthan about 50 gsm.

Embodiment BH

The nonwoven laminate of any one of Embodiments BA to BG, wherein thelaminate comprises two facing layers positioned on opposite sides of theelastic layer.

Embodiment BI

The nonwoven laminate of any one of Embodiments BA to BH, wherein theelastic layer is meltblown and each facing layer is spunbond.

Embodiment CA

A process for producing a meltspun, preferably meltblown or spunbond,fiber comprising:

(i) forming a polymer blend comprising from about 45 to about 85 wt % ofan impact copolymer, where the impact copolymer comprises a blend offrom about 40 to about 85 wt % of an impact copolymer and from about 15to about 60 wt % of a propylene-based elastomer,

wherein the impact copolymer is a reactor blend and comprises apropylene homopolymer component and a copolymer component, where thecopolymer component comprises less than 55 wt % ethylene-derived units,based on the weight of the copolymer component; and

wherein the propylene-based elastomer comprises propylene and from about5 wt % to about 25 wt % units derived from one or more C₂ or C₄-C₁₂alpha-olefins and has a MFR of greater than about 20 g/10 min and a heatof fusion less than about 75 J/g; and

(ii) forming fibers comprising the polymer blend.

Embodiment CB

The process of Embodiment CA further comprising (iii) forming a nonwovenlayer from the fibers.

Embodiment CC

The process of Embodiment CA or CB, wherein the process furthercomprises forming an elastic nonwoven layer and combining the elasticnonwoven layer with the nonwoven facing layer to form a nonwovenlaminate.

Embodiment CD

The process of any one of Embodiments CA to CC, wherein the nonwovenfacing layer and the elastic nonwoven layer are produced in a singleintegrated process.

Certain embodiments and features have been described using a set ofnumerical upper limits and a set of numerical lower limits. It should beappreciated that ranges from any lower limit to any upper limit arecontemplated unless otherwise indicated. Certain lower limits, upperlimits and ranges appear in one or more claims below. All numericalvalues are “about” or “approximately” the indicated value, and take intoaccount experimental error and variations that would be expected by aperson having ordinary skill in the art.

As used herein, the phrases “substantially no,” and “substantially freeof” are intended to mean that the subject item is not intentionally usedor added in any amount, but may be present in very small amountsexisting as impurities resulting from environmental or processconditions.

To the extent a term used in a claim is not defined above, it should begiven the broadest definition persons in the pertinent art have giventhat term as reflected in at least one printed publication or issuedpatent. Furthermore, all patents, test procedures, and other documentscited in this application are fully incorporated by reference to theextent such disclosure is not inconsistent with this application and forall jurisdictions in which such incorporation is permitted.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A fiber comprising a blend of from about 30 toabout 85 wt % of an impact copolymer and from about 15 to about 70 wt %of a propylene-based elastomer, wherein the impact copolymer is areactor blend and comprises a propylene homopolymer component and acopolymer component, where the copolymer component comprises less than55 wt % ethylene-derived units, based on the weight of the copolymercomponent; and wherein the propylene-based elastomer comprises propyleneand from about 5 wt % to about 25 wt % units derived from one or more C₂or C₄-C₁₂ alpha-olefins and has a MFR of greater than about 20 g/10 minand a heat of fusion less than about 75 J/g.
 2. The fiber of claim 1,wherein the fiber comprises from about 45 to about 65 wt % of thepropylene-based elastomer.
 3. The fiber of claim 1 or 2, where thepropylene homopolymer component has a MFR of greater than 100 g/10 min.4. The fiber of claim 1, where the propylene homopolymer component has aMWD of from 1.0 to 7.0.
 5. The fiber of claim 1, where the copolymercomponent of the impact copolymer comprises from about 35 to about 55 wt% ethylene-derived units, based on the weight of the copolymercomponent.
 6. The fiber of claim 1, where the copolymer component of theimpact copolymer comprises from about 40 to about 52 wt %ethylene-derived units, based on the weight of the copolymer component.7. The fiber of claim 1, where the copolymer component of the impactcopolymer comprises from about 43 to about 50 wt % ethylene-derivedunits, based on the weight of the copolymer component.
 8. The fiber ofclaim 1, where the impact copolymer comprises from about 40 to about 95wt % of the propylene homopolymer component and from about 5 wt % toabout 60 wt % of the copolymer component.
 9. The fiber of claim 1, wherethe impact copolymer has an ethylene content of from about 3 wt % toabout 40 wt %, based on the weight of the impact copolymer.
 10. Thefiber of claim 1, where the propylene-based elastomer is a reactor blendof a first polymer component and a second polymer component.
 11. Thefiber of claim 10, where the first polymer component comprises propyleneand ethylene and has an ethylene content of greater than 10 wt %, basedon the weight of the first polymer component.
 12. The fiber of claim 10,where the first polymer component comprises propylene and ethylene andhas an ethylene content of from about 10 to about 20 wt %, based on theweight of the first polymer component.
 13. The fiber of claim 10, wherethe second polymer component comprises propylene and ethylene and has anethylene content of greater than about 2 wt %, based on the weight ofthe second polymer component.
 14. The fiber of claim 10, where thesecond polymer component comprises propylene and ethylene and has anethylene content of from about 2 to about 10 wt %.
 15. The fiber ofclaim 10, where the propylene-based elastomer comprises from 3-25 wt %of the second polymer component, based on the weight of thepropylene-based elastomer.
 16. The fiber of claim 10, where thepropylene-based elastomer has an MFR of greater than 40 g/10 min. 17.The fiber of claim 10, further comprising a slip additive.
 18. The fiberof claim 10, wherein the fiber has a monocomponent structure.
 19. Thefiber of claim 10, wherein the fiber has a peak elongation of greaterthan 175%.
 20. A nonwoven composition comprising a blend of from about30 to about 85 wt % of an impact copolymer and from about 15 to about 70wt % of a propylene-based elastomer, wherein the impact copolymer is areactor blend and comprises a propylene homopolymer component and acopolymer component, where the copolymer component comprises less than55 wt % ethylene-derived units, based on the weight of the copolymercomponent; and wherein the propylene-based elastomer comprises propyleneand from about 5 wt % to about 25 wt % units derived from one or more C₂or C₄-C₁₂ alpha-olefins and has a MFR of greater than about 20 g/10 minand a heat of fusion less than about 75 J/g.
 21. The nonwovencomposition of claim 20, where the composition is spunbond.
 22. Thenonwoven composition of claim 20, where the composition has a basisweight of less than 50 gsm.
 23. A nonwoven laminate comprising anelastic layer and at least one facing layer, wherein the facing layercomprises the nonwoven composition of claim
 20. 24. The nonwovenlaminate of claim 23, wherein the facing layer further comprises fromabout 1 to about 5 wt % of a masterbatch comprising a slip additive. 25.The nonwoven laminate of claim 23, wherein the facing layer is formedfrom monocomponent fibers having a thickness from about 0.5 to about 10denier.